Many methods and apparatuses for such purpose are known and conventional.
Austrian Pat. No. 342,697 for example discloses a cable saddle for securing heavy cables in cable shafts or chutes, having a shell portion to which the cable is secured, and a number of support rollers, projecting beyond the shell portion and removably secured thereto, for pulling the cable into place.
In practice however, it has been found that the known art suffers from a number of disadvantages. Thus, heavy cables can be laid and secured only in cable shafts or chutes, so that, besides the high level of costs for the cables themselves, equally high costs are also incurred for erecting the cable shaft.
It is also known and conventional for cables to be laid directly in the ground to avoid the high costs of building cable shafts or chutes. This manner of laying cables suffers from a number of disadvantages, in regard to heavy cables. On the one hand, heavy cables must be laid in such a way that they can accommodate changes in length which occur as a result of changes in temperature, without high axial tensile or compression stresses being applied to the cable and damaging it. This is not possible when heavy cables are laid in the ground, as the cables do not have any freedom of movement if they are surrounded over their entire circumference with earth, shingle, sand or the like. On the other hand, it is necessary for the cable to be embedded in the earth over the entire circumference of the cable, in order to absorb any short-circuiting forces without the cable being damaged or shifted in position.
Laying cables in the ground also suffers from the disadvantage that a defective cable can only be replaced or exchanged after it has been completely dug up, and this gives rise to high costs and requires a considerable amount of time.
The known methods of laying cables also suffer from the disadvantage that the cables which are laid in a cable shaft or chute or in the ground cannot additionally be cooled with a cooling medium so that the power to be transmitted cannot be increased or, for a given power, the cable cross-section cannot be reduced and the cable therefore cannot be reduced in cost.
In addition, the prior art suffers from the disadvantage that, during the operation of pulling the cable into place, the cables are subjected to a high axial tensile loading as they are unrolled from a supply drum and are drawn into the desired position by being subjected to a high pulling force. This high pulling load on the cable results in many cases in damage to the sheathing of the cable and to the cable itself.